Objectives: To determine the maximum tolerated dose, spectrum of toxicity, and response of persistent and recurrent ovarian carcinoma to intraperitoneal injection of a conjugate of rhenium 186 (186Re) and a monoclonal antibody; to measure the radiation distribution to normal structures; and to establish the fate of the infused isotope.
Methods: Rhenium 186 was conjugated to murine monoclonal antibody NR-LU-10, which binds to a cell surface antigen present on ovarian carcinoma. In a dose-escalating phase I trial, a single dose of 25 mg/m2 of antibody complexed with 25-150 mCi/m2 of 186Re was administered intraperitoneally to 17 women with ovarian carcinoma that was recurrent or persistent after platinum-based chemotherapy.
Results: Severe myelosuppression was observed at 150 mCi/m2 of 186Re in two evaluable patients. Other clinically significant toxicities included low-grade fever and transient skin rash. Hepatic enzyme elevation was seen in 12 of 17 patients, but was not clinically significant. No chronic enteric toxicity was observed. Decreased tumor size was demonstrated by repeat operation in four of seven patients with disease measuring less than 1 cm at the time of treatment (four of 17 total). All four responders had serum CA 125 levels of 35 U/mL or less at the time of treatment and had received only one regimen of chemotherapy.
Conclusion: This immunoconjugate can be administered intraperitoneally with acceptable toxicity and produces objective responses after a single dose in patients with minimal objective disease.